diff --git a/app/controllers/autocomplete_controller.rb b/app/controllers/autocomplete_controller.rb
index 5d81a996fba009b00f3bd295fb15c237ed4a6bc5..1e4fc612a3cd86517787d55e0c92e6b0d220f50a 100644
--- a/app/controllers/autocomplete_controller.rb
+++ b/app/controllers/autocomplete_controller.rb
@@ -15,7 +15,7 @@ class AutocompleteController < ApplicationController
         @users = [*@users, current_user]
       end
 
-      unless params[:author_id] == "false"
+      if params[:author_id] && params[:author_id] != "false"
         @users = [User.find(params[:author_id]), *@users]
       end
 
diff --git a/app/models/concerns/issuable.rb b/app/models/concerns/issuable.rb
index f9314a241b296fb8ae24575dfdb75838a219c8f7..e5f089fb8a0976a5e638e488c4df59c1f11b7814 100644
--- a/app/models/concerns/issuable.rb
+++ b/app/models/concerns/issuable.rb
@@ -116,11 +116,6 @@ module Issuable
     assignee_id_changed?
   end
 
-  def can_assign_user?(current_user)
-    author == current_user ||
-    Ability.abilities.allowed?(current_user, :"admin_#{to_ability_name}", project)
-  end
-
   def open?
     opened? || reopened?
   end
diff --git a/app/services/issuable_base_service.rb b/app/services/issuable_base_service.rb
index 99a28b8c637bc110f8611f62cf5b18bc05f515a7..ca87dca4a7067e735757ddd831b48937dc2a1c54 100644
--- a/app/services/issuable_base_service.rb
+++ b/app/services/issuable_base_service.rb
@@ -33,7 +33,7 @@ class IssuableBaseService < BaseService
     end
   end
 
-  def filter_params(issuable_ability_name, issuable)
+  def filter_params(issuable_ability_name = :issue)
     params[:assignee_id]  = "" if params[:assignee_id] == IssuableFinder::NONE
     params[:milestone_id] = "" if params[:milestone_id] == IssuableFinder::NONE
 
@@ -42,18 +42,13 @@ class IssuableBaseService < BaseService
     unless can?(current_user, ability, project)
       params.delete(:milestone_id)
       params.delete(:label_ids)
-
-      # The author of an issue can be assigned, to signal the ball being in his/her
-      # court. This allow him/her to reassign the issue back to the reviewer.
-      if issuable && !(issuable.author == current_user)
-        params.delete(:assignee_id)
-      end
+      params.delete(:assignee_id)
     end
   end
 
   def update(issuable)
     change_state(issuable)
-    filter_params(issuable)
+    filter_params
     old_labels = issuable.labels.to_a
 
     if params.present? && issuable.update_attributes(params.merge(updated_by: current_user))
diff --git a/app/services/issues/base_service.rb b/app/services/issues/base_service.rb
index 4527d1c74e0d9c25abaa7b01bf6a55c45ce4de12..770f32de9448277bdbc9c7d6cc74ecf5c70b7cad 100644
--- a/app/services/issues/base_service.rb
+++ b/app/services/issues/base_service.rb
@@ -10,8 +10,8 @@ module Issues
 
     private
 
-    def filter_params(issuable = nil)
-      super(:issue, issuable)
+    def filter_params
+      super(:issue)
     end
 
     def execute_hooks(issue, action = 'open')
diff --git a/app/services/merge_requests/base_service.rb b/app/services/merge_requests/base_service.rb
index e472381ba362f0fc7db77fb383c04ff067d1be9e..7b306a8a5319d3a347a0f19e550ca0962b41fd7d 100644
--- a/app/services/merge_requests/base_service.rb
+++ b/app/services/merge_requests/base_service.rb
@@ -23,8 +23,8 @@ module MergeRequests
 
     private
 
-    def filter_params(issuable = nil)
-      super(:merge_request, issuable)
+    def filter_params
+      super(:merge_request)
     end
   end
 end
diff --git a/app/views/shared/issuable/_sidebar.html.haml b/app/views/shared/issuable/_sidebar.html.haml
index 1df44eaa64f2b202abea860253dd38fabc412c0d..ef351fe80936325bed9433d6d97853e4900d4f81 100644
--- a/app/views/shared/issuable/_sidebar.html.haml
+++ b/app/views/shared/issuable/_sidebar.html.haml
@@ -30,7 +30,7 @@
         .title
           %label
             Assignee
-          - if issuable.can_assign_user?(current_user)
+          - if can?(current_user, :"admin_#{issuable.to_ability_name}", @project)
             .pull-right
               = link_to 'Edit', '#', class: 'edit-link'
         .value
diff --git a/spec/controllers/autocomplete_controller_spec.rb b/spec/controllers/autocomplete_controller_spec.rb
index 0754a2889fcde58a35add959f1cabb61e77760bf..612e344c4118b6dca7a9e69810a482a27e00cd72 100644
--- a/spec/controllers/autocomplete_controller_spec.rb
+++ b/spec/controllers/autocomplete_controller_spec.rb
@@ -12,13 +12,13 @@ describe AutocompleteController do
       project.team << [user, :master]
     end
 
-    let(:body) { JSON.parse(response.body) }
-
     describe 'GET #users with project ID' do
       before do
         get(:users, project_id: project.id)
       end
 
+      let(:body) { JSON.parse(response.body) }
+
       it { expect(body).to be_kind_of(Array) }
       it { expect(body.size).to eq 1 }
       it { expect(body.first["username"]).to eq user.username }
diff --git a/spec/models/concerns/issuable_spec.rb b/spec/models/concerns/issuable_spec.rb
index 16fc1a6069acf27e5ba5f79297287eb600838a23..600089802b2a4bed2e4eb4e8c49551845b2dfa93 100644
--- a/spec/models/concerns/issuable_spec.rb
+++ b/spec/models/concerns/issuable_spec.rb
@@ -111,20 +111,6 @@ describe Issue, "Issuable" do
     end
   end
 
-  describe "#can_assign_user?" do
-    let(:author)  { build(:user) }
-    let(:issue)   { build(:issue, author: author)}
-
-    it "Allows the author to change the assignee" do
-      expect(issue.can_assign_user?(author)).to be_truthy
-    end
-
-    it "Doesn't allow others, non-team members" do
-      other_user = build(:user)
-      expect(issue.can_assign_user?(other_user)).to be_falsey
-    end
-  end
-
   describe "votes" do
     before do
       author = create :user